Field of the Invention
The present invention relates to a measurement system, which comprises a force cell for detecting a support force in a support structure, particularly for detecting a support force in a support element which forms a part of the support structure. The support structure is applied to a statically erected crane, a supported working machine, a travelable crane vehicle, a travelable crane, a drilling vehicle, a self-propelled carriage, etc., which hereinafter are all referred to as a working machine or a machine.
Description of the Background Art
FIG. 1 schematically shows a crane vehicle 1, which is used at a fixed position and stands on a support element 2 during the work, and the support element may also be referred to as a support leg here. The support element 2 is located in a bottom region of outwardly extendable brackets 3, and the brackets are fixed on a frame 44 of the vehicle. Each of the brackets 3 is configured to be a retractable bracket, and the bracket may be disposed in a working position, where the bracket laterally stretches out of the vehicle, from the frame 44 by means of a linear motion with or without the aid of an external force. It is also possible for the bracket 3 to be pivotably configured such that the bracket 3 can, by the aid of an external force if necessary, pivotally move around a vertical or horizontal axis to move to the working position where the support laterally stretches out of the vehicle. End regions of the bracket may also move to the working position by means of the combined pivotal and telescopic motions. In this case, the bracket is length-adjustable (retractable) itself, and has one end thereof pivotably disposed on the vehicle. In another configuration, the bracket may also comprise a plurality of turnover links, so that the bracket may be turned over into the working position following a folding motion. The telescopic motion, pivotal motion and a combination thereof are covered by the term “outwardly extending motion (drawn out or stretched out)”.
At the position of use, the whole crane vehicle (generally a machine) is preferably lifted up in a hydraulic manner by means of a support element 2, wherein the support element 2 may previously extend outwardly in a hydraulic manner onto the bracket 3 thereof. If there is a wheel, this is usually not in contact with the ground, but it at least reduces the load.
If the force vertically transferred to the ground via the support element is measured, the weight distribution of the whole system (i.e., the supported machine comprising the carried load) and therefore the center of gravity of the whole system may be determined, particularly when lifting the load. The measured value is configured to be used to determine the dumping point of the machine or the crane. It is possible to measure the support force in that a force cell is located in a line of force of each support element. Thus, the force cell outputs a signal corresponding to the respective support force, and the signal is analyzed by the above-mentioned method, for example.
Application EP 2159428, which corresponds to U.S. Pat. No. 8,516,945, shows a solution for coupling or connecting a sensor to a crane. The solution uses a sliding contact connection on a central tube to transmit signals. Using this solution may only achieve a single-pole solution. Hence, the vehicle mass body of the crane has to be used as a second pole. However, this will cause conduction current and failure in the case of wet ground or when it rains, and therefore in this regard, the signal will increase the burden of failure. Furthermore, in principle the danger is in that the connection within the cylinder block is interrupted by the open sliding contact.
Furthermore, a single line connection is unsuitable for common techniques requiring a multi-pole connection. Thus, a reliable connection, such as Canbus, needs at least five poles, and a 4-20 mA technique needs a two- or three-pole connection.